Classic Tic Tac Toe has a solved strategy. This project's question: what breaks that?
Expanding to 4D creates a board too complex to solve mentally. Adding simultaneous turns removes the ability to react — both players commit before seeing the result.
The UI was the hardest part. Representing 4D space in 2D without losing spatial intuition required iteration. The final solution uses a 4x4 grid of 4x4 boards, color-coded by depth dimension with a subtle perspective transform to hint at the third and fourth axes.
Playtesting revealed something unexpected: players developed intuition for 4D space faster than anticipated. The game works because the mind adapts.